Electric smelting.



G. H. BENJAMIN. ELECTRIC "SMLLTING APPLICATION FILED Nov. a, 1911.

Patented Jan. 21, 1913.

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' ELECTRIC SMELTING. APPLIAOATION FILED Nov. e, 1911.

Patented Jan 21, 1913.

2 SHEETS-SHEET a.

GEORGE BILLARD BENJAMIN, or NEW YORK, N. Y.

ELECTRIC SMELTING.

nuances.

`Speeicaton of Letters Patent.

Patented Jan. 21, 1913.

Aplication l'ed November 6, 1911. SeralNo. 658,775.

vin an electric furnace for the removal of phosphorus, fit has -been found practically impossible to remove substantially all the phosphorus Aand yet leave the Vrequiredamount of carbon associated with the iron. The reason for thisappears to be that the lime introduced into the furnace, has greater aiiinity for the carbon than for the phosphorus. Under the high temperature of the furnace there willbe formed in the prelimi narystages of the treatment, calcium carbid, calclum phosphid and calcium silicid. If the treatment is carried on for any length oftime, there will be continuous combination of the carbon with the lime, the phosphorus,

however, remaining uncombined until all of the 'carbon is absorbed, when combination with the remaining phosphorus will take place. A

My invention has 'nfor its object to over'- come the objection stated, and eect smelting insuch a manner that in the case of steel,

.definite grades of steel may be obtained, and

in the case of other metals, definite combinations.

The accompanying drawings` illustrate apparatus which may be used to carry my p,

- invention into effect. vI wish .it understood,

. nished body.

however, that these drawings are merely` p illustrative of/types of .suchv apparatus as may be employed.

l In the drawings, Figure 1 illustrates in be employed in converting an ore into -a Anished body, and Fig. 2 illustrates, in vertical section, such a construction aspmay be employedv in converting a fluld body linto a -Tocarry my invention i into "1 may proceed as follows, reference being firstv had toF-ig. 1. Roastedv ore yis'charged `into a ,stack 10 ofthe furnace marked gland falls the hearth. ii.. a .Situated the smelting chamber 12 of this furnace, are electrodes 13 connected to any suitable source of electricity. Simultaneously with the introduction -of the ore, there is charged such fluxes as are known to be useful in producing the reduction of the ore in electric furnaces, preferably,` among others, lime and carlbon, lwhich, as described in my prior yPatent No. 834,656 dated October 30th, 1906, will combine, together with the m'lioon and phosphorus carried by the ore, to form calcium carbid, calcium phosphid and cal` cium silicid, all of which reactions are now well understood. In late experiments Ihave found it advisable to introduce magnesia, which combines with the nitrogen present to form magnesium nitrate. The furnace A is. provided with a slag door 14,' through ,which the slags may be withdrawn, and with an exit doorsl through which the contents of the furnace-may bev continuously or intermittently discharged' into a passageway 16, communicating with a second furnacefB.. The furnace B is substantially the same in construction as the furnace A at the right, with the exception that it is not provided -withthe stack 10. Situatedover this furnace are bins 17, 18-19, adapted to con-tain 4such materials as it'may be desired to incorporate in the steel, as for instance, carbon., nickel, vanadium, or other materials. Under the bins is a hopper 20, through which a charge may be accumulated to .be subsequently dumped into the molten bath on'thel t@ vhearth ofthe furnace B.- 21 indicates a hopper arranged over` .the passageway 167:' through which any desirable material may be charged into the molten metal as it flows' from the furnaceA to the furnace B. y 22%A and 23 are respectively slag and exit doors from the furnace B. In out my' rocess I charge'the ore (roasted, concentrated or otherwise) together with the=uxes.,. into'the stack 10, Vand after it has been sa# ciently heated,on to the hearth ofthe-fur@ nace A, and therein subject' the combinedv bodies tothe temperature eeicts of amitted 'electric' current until all ofthe. car-Ql hon (except that which forms amnstituen element off-the electrodes} silileen andpliosj phorus' present'. have'cemhined' 'with .the in trcduced limegfIn case magasiniers beers ice charged intolvthe furnace,l the whatwe? a portion 'ofthefwgli hw* bined with the. ,"Thetime recante@ te eeetthe: -dependmme what upon the nature of the charge and construction of the furnace-usually from five to seven hours will be required. After the combinations above outlined have been cffected, the metal on the hearth will be substantially pure iron. At this time the exit door l5 of the furnace A is opened, and the substantially pure iron caused to traverse the passageway 16 and be discharged upon the heart-h of thefurnace B. As pure iron is not readily maintained fluid, or sufficiently fluid to cause it to run freely or to be readily mixed with the materials introduced in the furnace` B as hereafter described, I prefer to introduce into the iron, before it leaves the furnace A or as it traverses the passageway 16, a certain amount of powdered silica, which tends to increase ,the fluidity of the iron. If the temperature of furnace A is, however, sufficiently high, this step may be omit-ted. After the pure iron has been discharged into the furnace B and therein subjected to the temperature effects of a transmitted electric current of this furnace, I introduce int-o the iron, a definite amount of carbon, or a definite amount of carbon and any other material, such as nickel, or vanadium, as may be required to produce steel of the character desired. Further, I .may add an acid or an alkali, or other suitable material, as a catalytic agent., to aid in bringing about a uniform mixture and combination of the viron bath and the introduced materials. In practice it has been found, that in the furnace B it is not necessary to maintainthe saine degree o f temperature as in the furnace A, and probably for the reason that in the furnace A the temperature mustV be sufiiciently high to break down the chemical bonds existing between the materials combined in the ore and to. effect the required combinations with the lime, whereas in furnace B all that is required is to bring about the cdmbination of the carbon with the iron and the alloying'or amalgamation ofthe nickel, vanadium or other material with the iron and carbon, Any slags which form in the furnace B may be drawn off through the door 22 and the finished metal throug the exit door23. The time of treatment in the furnace B will depend largely upon the refractory character ofthe introduced materialsgenerally from three to five hours will be found sufficient.

The process asl described involves an intermittent action, that is to say, first breaking down the materials in furnace A. and subsequently building up the materials 1n furnace B. It is within the contemplation of my invention, ess a continuous one, that is, that the pure iron as it forms on the hearth of furnace A should continuously run into furnace B. It is likewise within the contemplation of my furnace to perform all of the operations rehowever, to make the procy quired, in furnace it has been found same results, slugs which the furnace, with the iron A. In practice, however, diliicult to accomplish the and for the reason that the accumulate upon the walls of tend to become reincorporated at the time when the materials like carbon, nickel and vanadium are reintroduced. I therefore prefer to carry out the operations in two furnaces as described.

Referring now to Fig. 2, my improved method is carried into effect as follows: Basic fluxed steel is accumulated in the mixer 30 and discharged through door 3l from the mixer into the tilting furnace A, and therein subjected to thetemperature effects of a transmitted electric current, and the introduced fluxes, such as have been described. This furnace is provided with a slag door 32 and an exit or pouring door 33; After the required rea tions have been effected, the furnace is tilted and the fluid metal discharged into the furnace B,'Where it is again subjected to the temperature effects of a transmitted electric current. Into the metal in this described in the furnace shown in' Fig. l as pure iron, there is introduced carbon, nickel or vanadium, or any other material with which it is desired to combine' the iron. Fluxe's and catalytic agents may be introduced. The furnace may be tilted to aid in effecting the combinations. In case of the formation of a slag, it may be discharged through the slag door 34, and the finished metal through the exit door 35, into a ladle 36. 'i

In carrying out. the operations described, the furnaces in Fig. l and Fig. 2 may have acid or basic linings, depending upon the materials treated. I do not limit myself in any Wise to the character of the lining, fluxes or catalytic agents which may be introduced, or to the temperatures which may be employed, provided they are suliicient to effect the chemical actions and reactions described. lVhat I wish to have understood is that I believe I am the first to recognize the fact that it is impossible to obtain a uniform grade of steel in an electric furnace, and at the same time reduce the phosphorous constituent in an amount which will not be objectionable in the finished product and to suggest a method of treatment and means by which the required results can be obtained.`

I have described my.-improved process as employed in the manufacture of steel. Manifestly it may be employed in the treatment of other met-als, such as zinc and copper,

or in the manufacture of alloys-and generally in metallurgical operations where it isdesired lto free the original ore or metal from bodies, before with other bodies. I 4

In describing the application of-Iny 1m' effecting combinations claim:

proved method as relating to the furnace constructionfasshown in Fig. 1,1 have stated lthatthe 'materials discharged into the stack` 10'a're hea-ted,.:vvliich heating it 'will be seen 1s d1 1e-" t` o "th-fefheat generated due to atransmitted-'electric.current ascending the stack.

Having .thusfdescribed my invention,I I

1. The hererfdescribed -process which consists in subjecting a charge containing carbon and phosphorus to the action of -l'uxes containinglime in excess of that re- I* quired to combine with the carbon present,

and to' the high temperature eiects of a transmittedelectric current, until substan-- tially all of the 'carbon and phosphorus present has been 'combined With the lime,

then subjectingthe metal after separation of theslag, to the high temperature effects' of a transmitted electric current and While soh'eated introducing suchmaterials as-are required to produce the productdesired.

2. The jherein described process which consists. in subjecting la charge containing y carbon-and phosphorus first to the action of heat a'iidv'luxes, then to the action ofthe high temperature effects of ajjtransmitted v-electric current, and fluxes containing lime lin excess' of that required to combine with the carbon', until substantiallyla'llj of the' carbon and phosphorus present'A has been combinedWit-h the lime,A then removing the slag,.then subjectingthe resultant-metal to `the high temperature eiiects of a transmitted electric current, and While so heated introducing such materials -as are required y' to 'produce the product desired.

3. The vherein described process `which .consists in introducing acharge'containing fluxes containing ylime in 'tially all of the'carbon' and phosphorus carbon and phosphorus into a iurnace, thenl subjecting the material to the action of basic quired to combine Y With the carbon present, and tothe high temperature eects of a transmitted electric. currei'it, until substanexcess or that re`.

-lluxes containing lime in excess of that required to combine -With the carbon present,

land to the high temperature effects of a transmitted electric current, until substantially all of the carbon and phosphorus has 60 been combined With the lime, then 'removing the slag, then subjecting thel resultant metal to the high temperature eiiectsgof a transmitted electric current but of relatively lower temperature than that to which' it was first 65 subjected, and While so heated* introducing'- such materials as `are required'to produce vthe-product desired.

5. A step in the-process described, which consists' in eliminating substanitiall all'or'e the carbon and phosphorus from a charge containing iron, -carbon and phosphorus Without effecting oxidation of these bodi'es,f

before introducing' the carbon constitueht/ required to produce. a; steel. v 6: A step in the. process described, Which .consists in subjecting a. charge conaining j iron and nit-rogento the' high temp rature effects of a transmitted .electriccurrent 80 to the action of magnesiasuiiicient inv quantity to satisfy the nitrogen present, whereby chemical combinationWit-h the nitrogen is effected, and the nitrogen removed from the' charge treated.

In testimony vv ereof, I. aiixrmy s igiia'-l A j ture, the presence of twowitnesses.: .l

stores mttiiin iiiiimui'i'iit',

definite grade 

